1. Field of the Invention
The present invention relates to disk drive apparatuses for recording and reproducing (reading) data into and from disks for which data is rewritable, such as compact discs rewritable (CD-RWs), and to disk formatting methods.
2. Description of the Related Art
Recording media for storing a large amount of data are usually formatted logically in units of addresses. Disk-shaped recording media and tape-shaped recording media used for computers, for example, usually have numbered sectors divided into several areas and numbered tracks.
These recording media usually have overhead information including additional error-detecting and error-correcting bits, synchronization patterns formed of bits used for synchronizing clocks before reading or writing, and an unused space for adapting to differing speeds among drives. The overhead information (including sector address numbers, synchronization patterns, and a gap of the unused space) is separately written in a process called formatting.
CD-type disks, generally called compact disks, have a single helical data track starting from the center (inner periphery) of the disk and ending at an end (outer periphery) of the disk. Recordable disks and rewritable disks, such as compact discs recordable (CD-Rs) and CD-RWs, have a helical data track formed of a physical groove. In contrast, reproduction-only (read-only) disks, such as compact discs digital audio (CD-DAs) and compact discs read-only memory (CD-ROMs), have no physical groove serving as a data track.
In a CD-type signal format, bytes of data are arranged in units of frames, frames of data are arranged in units of sectors, and sectors serve as the minimum addressable units.
One frame has 2,352 bytes of data. Frame addresses are indicated by a time and a frame offset. More specifically, frame addresses are expressed by {M, S, F}, where M indicates the minutes, S indicates the seconds, and F indicates the frame offset within one second. One second includes 75 frames.
These frame addresses (MSF addresses) may be absolute (measured from the beginning of the physical data track) or may be relative (measured from the beginning of the current logical data track).
Frames of data may be arranged in units of packets. One packet has one link frame, four run-in frames, an actual data frame, and two run-out frames.
CD-Rs have variable-length packets. CD-RWs have fixed-length packets in which a total of 39 frames (32 actual data frames and seven overhead frames) are included per packet in the current formatting standard.
In the format for CD-DAs and CD-ROMs, a so-called lead-in area disposed near the beginning of the physical data track and the following program area are required. The program area is formatted in units of logical data tracks. In the format of CD-DAs and CD-ROMs, a so-called lead-out area disposed at the end of the last logical data track is also required.
Reproducing (reading) apparatuses for CD-DAs and CD-ROMs can search for a particular logical-data-track number. For this search, the lead-in area includes TOC information (table-of-contents information) and the TOC information includes absolute MSF address information for logical data tracks. The lead-in area also includes a pointer pointing to the lead-out area.
In many drive apparatuses, since servo calibration cannot be achieved in the radial direction, data cannot be read from disks unless both the lead-in area and the lead-out area exist.
As described above, CD-Rs and CD-RWs have a physical groove in which data is recorded, but reproduction-only (read-only) disks (CD-DAs and CD-ROMs) have no physical groove. In the reproduction-only (read-only) disks, a helical path formed of data pits and lands serves as a track which can be optically detected.
In many reproduction (reading) apparatuses, the number of times a pickup crosses the track formed of a pit string on the disk or the number of times the pickup crosses the groove is counted during movement in the radial direction.
Drive apparatuses for CD-Rs and CD-RWs have a groove detecting function, but drive apparatuses (reproduction-only (read-only) apparatuses) for CD-DAs and CD-ROMs may have no groove detecting function.
In some drive apparatuses, movement in the radial direction, which crosses a helical physical data track, may form an open loop, in which the number of times the physical data track is crossed is not increased.
Drive apparatuses which achieve an open-loop movement in the radial direction usually perform servo calibration in the radial direction by moving the pickup from the lead-in area to the lead-out area. Therefore, some drive apparatuses need to format all frames disposed between the lead-in area and the lead-out area.
After the format for CD-DAs and CD-ROMs had been developed, recordable (write-once) disks (CD-Rs) were introduced. CD-R recording has a very important feature of partially recording data into a disk and adding new data later. Since the original lead-in area cannot be changed in write-once disks when new data is added, this single lead-in area is insufficient. Therefore, a xe2x80x9csessionxe2x80x9d technique was introduced, and the physical data track is formatted to have a plurality of sessions. In this case, each session has one lead-in area and one lead-out area. Up to 99 logical data tracks can be formed over all sessions. Each lead-in area except that for the last session includes a pointer pointing to the frame address of the next (possible) session.
The format for CD-ROMs and other formats can currently have a multi-session function for formatting the physical data track to have a plurality of sessions.
After that, rewritable (erasable) disks (CD-RWs) were developed. Like magnetic disks and tape, CD-RWs need generalized random-access recording. It is also necessary to maintain lower compatibility with single-session disks (such as CD-DAs) and multi-session disks. For tape and magnetic disks, special-format magnetic heads can be manufactured in order to format the tape and magnetic disks to have many data tracks at the same time at a higher speed than the usual track speed. For CD-RWs, however, heating and a certain cooling speed are required to write each pit, and the speed is essentially low. Rewritable media use a transparent, phase-change material which can change its crystalline state reversibly when heated and then cooled at a certain controlled speed. To heat the material and then cool small areas at a certain required controlled speed, a laser is used. Therefore, it takes 40 to 80 minutes to format the entire CD-RW disk irrespective of whether formatting is performed by the medium manufacturer or in a drive. As a result, formatted CD-RWs may be very expensive for users. When the user needs to record data immediately, however, it may not be commercially acceptable that the drive apparatus of the user requires a period of 40 to 80 minutes for formatting a disk. Therefore, it is generally required that drive apparatuses partially format CD-RWs at a high speed in order to provide the usability of giving an initial state at a high speed and incremental recording of recording additional data.
As data recording methods for optical disks, such as write-once disks (CD-Rs) in which data is recordable, and rewritable disks (CD-RWs) into which data is again recordable in an overwriting manner, a track-at-once method and a packet-write method are used.
In the track-at-once method, data is recorded in a track at a time with one packet. User data blocks are continuous in the track, and a link block is not disposed between user data blocks. This track serves as a recording unit. Up to 99 tracks can be formed on a disk. Table-of-contents information (TOC), such as the starting address and the ending address of a track, is stored in an area different from that for recording user data.
In contrast, a track is divided into a plurality of packets, and data is recorded in units of packets in the packet-write method. Since data is recorded in units of packets, user data blocks are disposed in a discrete manner in one track and a link block is disposed between user data blocks.
The packet-write method includes two types, a fixed-length packet-write method and a variable-length packet-write method.
In the fixed-length packet-write method, a packet length indicating the number of user-data blocks in a packet is fixed in one track. In the variable-length packet-write method, packets having different packet lengths are disposed in one track. A universal disk format (UDF) is a file system using this fixed-length packet-write method. The UDF is used for various types of devices and is a file system using a recording format suited to the features of each device.
Since data is recorded additionally into CD-Rs, drive apparatuses only for CD-Rs just record data after recorded packets, even in recording in the packet-write method. Therefore, only additional writing is achieved by a so-called sequential UDF, which is a variable-length packet-write method. Formatting does not need to be taken into account.
In contrast, since data is overwritten in CD-RWs, drive apparatuses which can handle CD-RWs employ a random UDF, which records data in units of packets and reproduces (reads) data in units of blocks. In the random UDF, to allow data to be recorded and to be reproduced (read) at random, it is necessary to achieve formatting in which fixed-length packets are recorded in advance on the entire surface of a recording area or a specified area in a CD-RW to fill the recording area with fixed-length packets. This formatting allows data to be recorded and to be reproduced at random in the recording area of the CD-RW.
Formatting should be generally finished before variable data (such as user data) is written. Formatting takes much time in many cases. Therefore, recording media, such as flexible disks and tapes, are formatted in advance by manufacturers in some cases.
In other cases, formatting is achieved by apparatuses at the user side, such as disk drive apparatuses. When formatting is achieved at the user side, it is preferable that it does not take a long period of time to achieve formatting.
CD-RWs, which are rewritable disk recording media, are formatted in disk drive apparatuses at the user side in many cases.
A conventional example formatting operation for a CD-RW executed by a disk drive apparatus will be described below by referring to FIG. 1, FIG. 2, and FIG. 3.
FIG. 1 shows a formatting operation procedure achieved conventionally. This formatting operation is called a xe2x80x9cfull-formatting processxe2x80x9d for simplicity of description. FIG. 2 and FIG. 3 show a formatting operation procedure shorter than the xe2x80x9cfull-formatting processxe2x80x9d and it is called a xe2x80x9cUDF-grow-formatting processxe2x80x9d for simplicity.
The full-formatting process shown in FIG. 1 will be described below.
The entire disk area indicated in the figure means the entire area in which recording and reproduction (reading) are possible and which can be formatted in a CD-RW. The entire disk area does not include a power calibration area used for adjusting laser power or an intermediate recording area for recording intermediate management information obtained during a recording operation. (These areas, described later, are formed closer to the inner periphery of the disk than the lead-in area.)
In the full-formatting process, null data (=0) is written in the entire disk area in step ST1.
In the next step ST2, a lead-in area is formed at the innermost part of the disk and a lead-out area is formed at the outermost part in the entire disk area. The lead-in area stores management information generally called TOC (table of contents). The lead-out area indicates the end of the data recording area.
Then, in step ST3, the UDF file system is recorded immediately after the lead-in area and immediately before the lead-out area. The UDF (universal disk format) is an industry-admitted file system specification. System information is recorded according to the UDF specification.
In step ST4, verification is achieved for the area sandwiched by the lead-in area and the lead-out area, namely, a program area in which user data is recorded. The information recorded in the disk is read as verification data, and it is checked whether the correct data, namely, in this case, null data, is read. If incorrect verification data is read, it is determined that a portion (sector) which stores the data is defective, and a changing process is performed.
The changing process replaces the defective sector with a spare sector. Specifically, a sparing table for managing the defective sector and the new sector as a pair is updated.
The full-formatting process has been completed.
FIG. 2 and FIG. 3 show the UDF-grow-formatting process. This process indicates a formatting method called xe2x80x9cgrowing,xe2x80x9d specified in the UDF.
In this case, null data (=0) is written in a portion of the entire disk area in step ST11.
In the next step ST12, a lead-in area is formed at the innermost part of the portion where null data has been written and a lead-out area is formed at the outermost part.
Then, in step ST13, the UDF file system is recorded immediately after the lead-in area and immediately before the lead-out area.
In step ST14, verification is achieved for a program area sandwiched by the lead-in area and the lead-out area. According to the result of the verification, the changing process is performed. Specifically, the sparing table is updated.
Formatting is now completed for the portion in the entire disk area. Therefore, user data can be recorded into the program area of the formatted portion. As understood from the figures, the formatted portion includes the lead-in area, the program area, and the lead-out area.
It is assumed that data is gradually recorded into the formatted portion, as shown in step ST15. Recording progresses as indicated by an arrow xe2x80x9cRec.xe2x80x9d At some point of time, the program area becomes filled with data, and recording cannot be performed any more.
In such a case, extended formatting is executed.
As shown in step ST16, the lead-in area is deleted.
Then, the lead-out area is also deleted as shown in step ST17 illustrated in FIG. 3.
Null data is written into an extended area following the area where the data has been recorded, in step ST18. (In this step, the UDF file system, written in the area following the area where the data has been recorded, is overwritten and deleted.)
Verification is achieved for the extended area, and the sparing table is updated according to the result of the verification, in step ST19.
At this point of time, recording is possible. In step ST20, recording is executed from the data packet immediately following the data packets which have been recorded so far.
A partition map is appropriately adjusted in step ST21. A free-space map which indicates a new recordable area is updated in step ST22. An anchor volume description point is shifted according to the extension in step ST23.
Then, in step ST24, a new lead-in area is formed according to the achieved extension. In step ST25, a lead-out area is also formed.
In the UDF-grow-formatting process, a partial area is formatted first. When the recording capacity is running out as data recording progresses, the formatted area is extended by the process executed from step ST16 to step ST25.
Every time when the recording capacity runs out, extended formatting executed from step ST16 to step ST25 is performed. At the final stage, as shown in step ST26, the entire disk area is used.
The above-described formatting processes are executed according to instructions sent from a host computer, the processes including the full-formatting process in step ST1 to step ST4, first formatting in step ST11 to step ST14, and extended formatting in step ST16 to step ST25 of the UDF-grow-formatting process.
The full-formatting process or the UDF-grow-formatting process, described above, is conventionally applied to rewritable disks such as CD-RWs. These formatting processes take a very long time.
In the full-formatting process, since the entire disk area of a rewritable disk, such as a CD-RW, needs to be filled with fixed-length packets by null data or others, it takes a very long time. In addition, since user data cannot be recorded or reproduced (read) during formatting, the user has to wait for the formatting process to finish.
In the UDF-grow-formatting process, since formatting is first performed partially, the user waiting time is shorter than that in the full-formatting process.
In this case, however, since the lead-in area and the lead-out area are changed in extended formatting, a sufficient time reduction cannot be obtained.
The present invention has been made in consideration of the above situations. Accordingly, it is an object of the present invention to make the time for a formatting process for rewritable disks shorter.
The foregoing object is achieved in one aspect of the present invention through the provision of a disk drive apparatus for recording data into a rewritable disk by a fixed-length packet-write method and for reading recorded data, including formatting control means for applying a formatting process only to a local area which is a part of the entire recordable area of the rewritable disk and which does not include portions where a lead-in area and a lead-out area are to be formed; and recording control means for executing and controlling a data recording operation at an area formatted by the formatting control means.
The foregoing object is achieved in another aspect of the present invention through the provision of a disk formatting method for a rewritable disk in which data is recorded by a fixed-length packet-write method, including the step of applying a formatting process only to a local area which is a part of the entire recordable area of the rewritable disk and which does not include portions where a lead-in area and a lead-out area are to be formed.
The foregoing object is achieved in still another aspect of the present invention through the provision of a disk drive apparatus for recording data into a rewritable, optical disk and for reading recorded data, including: an optical pickup for emitting laser light in order to record data into the rewritable, optical disk and to read recorded data; formatting control means for applying a formatting process by the optical pickup only to a local area which is a part of the entire recordable area of the rewritable, optical disk and which does not include portions where a lead-in area and a lead-out area are to be formed; and recording control means for executing and controlling a data recording operation at an area formatted by the formatting control means.
In the present invention, formatting is applied not to the entire disk but to a local area which is regarded as the minimum required area. The local area does not include a lead-in area or a lead-out area.
With this formatting, a formatting process in which a fixed-length packet is filled with fixed data is quickly finished, and a user""s writing request is soon ready to be accepted.
With this operation, even in extended formatting, the deletion or re-recording of a lead-in area and a lead-out area is not performed, and the required time is reduced by the amount used therefor otherwise.
Conventionally, a lead-in area and a lead-out area are recorded in a formatting process. In the present invention, they are recorded when a disk ejection request is made if the user needs them (wants them). Therefore, an operation for recording a lead-in area and a lead-out area is executed only when it is required.